I have a '96 5 spd Accord with about 223k on it.

It still runs very good in general, but I've noticed a definate surge, mainly at low rpms (1000-2500)..more noticable with more load.

To me it doesn't seem like misfiring..the closest I can compare it to is an older carbed car that's cold. It sort of lightly surges through each gear, occasionally giving a pronounced buck. It's smooth at cruising speed.

I know it's not normal because when the engine is cold(open loop), it runs perfectly and very smoothly.

Something that might be related is I have a constant Check Engine light and the 2 codes that came up were for no power to the front and rear O2 sensors. I should have repaired that long ago but the car is dead reliable as it is, so...

Any ideas are appreciated...

 

Primary and secondary O2 sensor heaters are both dead? Maybe the voltage isn't getting to the heater elements because of a harness problem or blown fuse. Or, maybe they realy are dead. Anyway....

I experienced a similar surge on my old '90 Si. Slight buck/surge most noticeable at 25mph in 3rd gear at a steady throttle. No CEL though. In my case, the O2 sensor was slow and lazy. I replaced it with an OEM version after 2 generic types didn't work well. No problems after that.

A simple test you can try if you don't have access to a multimeter...
On a warm engine (closed loop), try to hold a steady 2200rpm in neutral. A slow and lazy sensor should cause the rpm to vary by 50 to 75 rpm or so. At least that's how mine acted.

 

Well the codes that are throwing are P0135 and P0141.

Doing some research, Civics around the year of mine had a problem chafing the harness through and blowing fuse 15. I'm not sure which fuse I should check on mine since it's an Accord...any ideas?

I recall reading a diagnosis on that exact problem that mentioned the "main relay" possibly being the cause...something about bad solder joints.

Thanks for the help....